(1) Field of the Invention
The present invention relates to a structure of unit pixel, and more specifically to the structure of unit pixel that is used in a LTPS (low temperature poly silicon) TFT LCD panel and that has micro transflective ability.
(2) Description of the Prior Art
According to the technology for constructing a display device of today, an LCD (Liquid Crystal Display) device is generally preferred to due to its compact size and quick response in addition to its lower power consumption and low radiation. Therefore, the LCD device is widely used in many electronic devices.
Note that the LCD device itself is not a light emitting instrument, and requires a light source to illuminate the crystal display panel. Generally, the crystal display panel is disposed adjacent to a light emitting path of a backlight module so that the light beams emitted from the backlight reaches the crystal display panel after passing through the diffusing film, the light guide plate and the other optical films. By adjusting or altering the orientation of the liquid crystal molecules in the crystal display panel, the brightness or illumination of the images can be controlled. Such type of LCD device is generally known as transmissive-mode because the light beams can pass through all the films.
When the transmissive-mode LCD device is used outdoor, the image or text is not easily viewable since the environmental light (such as sunlight) may overwhelm the light beams coming from the backlight module.
There is still another type of LCD device, namely, transflective mode. The transflective mode LCD device includes a light reflective structure that substitutes the backlight module and that is capable of reflecting the external light beams back into the crystal display panel, thereby increasing the utilization of the light beams so as to enhance the display ability of the images.
When the transflective mode LCD device is used indoors, one may encounter the problem of insufficient of brightness or light, since the lighting indoor cannot provide sufficient illumination to the crystal display panel, thereby leading to blurring of the images or text.
In order to solve the aforesaid disadvantage, a half transflective mode LCD device has been proposed and the latter includes a crystal display panel including a pixel unit having transmissive and transflective regions simultaneously.
Referring to FIG. 1, a half transflective mode LCD device is shown to include a plurality of scanning lines 11 and a plurality of data lines 12 disposed on a lower base plate 10 in a cross manner so as to define a plurality of pixel units 13.
Each pixel unit 13 includes a pixel electrode 131 and a TFT 132. The TFT 132 is coupled to the respective scanning and data lines 11, 12 and serves as the switch for the pixel electrode 131.
Note that the pixel electrode 131 can be further divided into a transmissive electrode region 1311 and a transflective electrode region 1312. The transmissive electrode region 1311 is made from a metal material, such as ITO (In Ti Oxide) while the transflective electrode region 1312 is made from a metal material having high reflectivity, such as aluminum.
FIG. 2 illustrates a sectional view of a conventional LCD device. When the external light beams L1 strikes the transflective electrode region 1312 after passing through the upper base plate 14, the light beams L1 reflect back to the upper base plate 14 so as to illuminate the crystal display panel. The light beams L2 emitted from the backlight module 15 pass through the transmissive electrode region 1311 and cooperates with the reflected light beams L1 to illuminate the crystal display panel. Thus, the user can select another type of LCD device when purchasing the display device.
However, the reflected light beams coming back from the aforesaid transflective electrode region 1312 cannot satisfy the requirement of the user of today LCD device as the development in the LCD technology further progresses. Therefore, for those skilled in the art, it has become an urgent task to explore how to increase the reflectivity ability so as to provide magnificent brightness in the crystal display panel of the half transflective mode LCD device.